The Wikibase extension ( that runs http://www.wikidata.org ) has a special page called SetAliases which can be see at https://www.wikidata.org/wiki/Special:SetAliases

When POSTing bad information to the special page an error is shown but the data is no longer retained in the html form for the aliases field. The task is to make the form retain this information after errors are displayed.

See this bug report for more information / queries.

Students are required to read Wikimedia's general Instructions first. Patches should be submitted to Gerrit and reference the bug report in the commit message.